Frankfurt show: Lexus trims GS450h thirst
BY RON HAMMERTON | 13th Sep 2011
The most fuel efficient GS variant will also be faster, powering from standstill to 100km/h in just 5.9 seconds – down from 6.2 seconds. This is just 0.2 seconds slower than the petrol-only GS350, with which it shares the same limited top speed of 250km/h.
Promising 18 per cent better fuel economy than the previous hybrid GS, the GS450h gets a revised 213kW 3.5-litre direct-injected Atkinson cycle V6 mated with the latest hybrid drive system for a combined 252kW of power and 345Nm of torque.
Combined-cycle fuel consumption is said to be 6.3 litres per 100km – down from 7.9L/100km in the current model – while CO2 emissions have been sliced from 186 grams per kilometre to 145g/km.
This compares with 6.1L/100km and 162g/km for the diesel BMW 535d and 6.3L/100km and 165g/km for the Mercedes-Benz E350 CDI.
The appearance of the GS450h at the world’s biggest motor show in Frankfurt follows the unveiling of the fourth-generation GS in its standard petrol GS350 guise last month at the Pebble Beach Concours d’Elegance in California.
The new GS range has been confirmed for a first-half arrival in Australian showrooms next year.
The GS450h looks much the same as the GS350 inside and out, but with the trademark blue-tinged badges that mark a hybrid variant.
The main news resides under the bonnet, where the Atkinson cycle V6 gets a super-high 13:1 compression ratio, new mid-port intake tumble generator and latest direct-inject technology with injectors in both the cylinder and manifold combining for optimum performance.
The engine adopts exhaust heat recovery to warm the engine coolant at startup to cut the engine warm-up time.
As before, the GS450h is a full hybrid, capable of operating in both petrol or electric modes or both, driving the rear wheels through a continuously variable transmission (CVT) with a six-speed sequential shift.
The vehicle will be available overseas in all-wheel-drive configuration, but only in cold-weather markets, not Australia.
Prius-style nickel-metal hydride batteries have been retained, but arranged in a new stacked configuration that Lexus says improves boot space.
The hybrid system’s regenerative braking operation range has been stepped up, while the cooling system of the Power Control Unit (PCU) has been improved.
As well, the PCU now boosts motor drive voltage to a maximum 650 volts in Sport mode, while limiting it to 500 volts in Eco mode.
Like the GS350, the GS450h is available with active four-wheel-steering, becoming the world’s first hybrid vehicle with such a system.
The electric-operated rear-wheel steering system alternates between turning in the opposite direction to the front wheels at speeds under 80km – albeit by small degrees – to the same direction over that speed to assist high-speed stability and handling.
The grilled of the GS450h appears essentially the same as that of the GS350, with the new ‘spindle’ design that marks a new direction in Lexus design language.
The all-new GS body is 20mm wider (1840mm) than that of the previous GS, while the track has also been widened by 40mm and 50mm at the front and rear respectively.
The bodyshell's torsional stiffness had been improved by 14 per cent – another factor in the claimed overall dynamic improvement in the car.
The current third-generation GS landed in Australian showrooms in February 2005, debuting with a 4.3-litre V8 and direct-injection in the 3.0-litre V6 – the first time this technology had been applied in a large luxury car.
The GS450h arrived in May 2006, when it became the first large hybrid luxury car on the Australian market.
